Not as simple as you told, what if you buy at higher price and then price going lownfor several months/several years? Waiting price for going back? It easy if you spend small amount, let say below $50K. But what if you spend more than $200K
If you are afraid that you will end up going all in at the top of the cycle, then DCA is the way to go. That way you don't have to worry about the current market price and try to (naively) time it to buy at the bottom.
With that being said, its much easier said than done as many give it up in the end, or eventually go all in.